ALESSANDRO RODRIGO BELON
Projetos de Pesquisa
Unidades Organizacionais
LIM/26 - Laboratório de Pesquisa em Cirurgia Experimental, Hospital das Clínicas, Faculdade de Medicina
12 resultados
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- Endovascular treatment of peripheral arterial injury with covered stents: an experimental study in pigs(2011) BELCZAK, Sergio; SILVA, Erasmo Simao da; AUN, Ricardo; SINCOS, Igor Rafael; BELON, Alessandro Rodrigo; CASELLA, Ivan Benaduce; GORNATI, Vitor; FIGUEIREDO, Luiz Francisco Poli deOBJECTIVE: To evaluate the feasibility of using endovascular repair to treat penetrating arterial injuries with covered stents. Feasibility was examined according to the circumferential extent of the injury. INTRODUCTION: Surgical trauma often increases the risk of major morbidity and mortality associated with vascular injury, and endovascular repair has many advantages in such situations. METHODS: Twenty white male domestic pigs weighing 28-38 kg with controlled vascular injuries were divided into four equal groups according to the circumferential extent of their vascular lesion (i.e., no lesion, lesion <50%, lesion >50%, and complete lesion). The left common carotid artery was dissected with proximal and distal control, and this procedure was followed by controlled sectioning of the arterial wall. Local manual compression was applied for 10 min and was followed by endovascular repair with the placement of a 5x50 mm VIABHAN (TM) covered stent using the femoral approach. We also monitored additional variables, such as the duration of the procedures (the mean was 56.3 +/- 19.1 min), ultrasound parameters (e.g., maximum arterial diameter, peak systolic and diastolic velocity, and resistance index), arteriography findings, and fluctuations in vital signs (e.g., cardiac output, arterial pressure, and central venous pressure). RESULTS: The experimental procedure was found to be feasible and reproducible. Repairs were successful in all animals in the control (no lesion) and <50% lesion groups. Success was also achieved in four out of five pigs in the >50% group and in one pig in the complete lesion group. DISCUSSION: The endovascular repair of an arterial injury is possible, but success depends on the circumferential extent of the arterial lesion. The present experimental model, which involved endovascular techniques, highlighted important factors that must be considered in future studies involving similar animals and materials.
- A simplified experimental model of large-for-size liver transplantation in pigs(2013) LEAL, Antonio Jose Goncalves; TANNURI, Ana Cristina Aoun; BELON, Alessandro Rodrigo; GUIMARAES, Raimundo Renato Nunes; COELHO, Maria Cecilia Mendonca; GONCALVES, Josiane de Oliveira; SOKOL, Suellen Serafini; MELO, Evandro Sobroza De; OTOCH, Jose Pinhata; TANNURI, UenisOBJECTIVE: The ideal ratio between liver graft mass and recipient body weight for liver transplantation in small infants is unknown; however, if this ratio is over 4%, a condition called large-for-size may occur. Experimental models of large-for-size liver transplants have not been described in the literature. In addition, orthotopic liver transplantation is marked by high morbidity and mortality rates in animals due to the clamping of the venous splanchnic system. Therefore, the objective of this study was to create a porcine model of large-for-size liver transplantation with clamping of the supraceliac aorta during the anhepatic phase as an alternative to venovenous bypass. METHOD: Fourteen pigs underwent liver transplantation with whole-liver grafts without venovenous bypass and were divided into two experimental groups: the control group, in which the weights of the donors were similar to the weights of the recipients; and the large-for-size group, in which the weights of the donors were nearly 2 times the weights of the recipients. Hemodynamic data, the results of serum biochemical analyses and histological examination of the transplanted livers were collected. RESULTS: The mortality rate in both groups was 16.5% (1/7). The animals in the large-for-size group had increased serum levels of potassium, sodium, aspartate aminotransferase and alanine aminotransferase after graft reperfusion. The histological analyses revealed that there were no significant differences between the groups. CONCLUSION: This transplant method is a feasible experimental model of large-for-size liver transplantation.
- Experimental rnodel of intracranial hypertension with continuous multiparametric monitoring in swine(2013) ANDRADE, Almir Ferreira de; SOARES, Matheus Schmidt; PATRIOTA, Gustavo Cartaxo; BELON, Alessandro Rodrigo; PAIVA, Wellingson Silva; BOR-SENG-SHU, Edson; OLIVEIRA, Marcelo de Lima; NASCIMENTO, Clarissa Nobrega; NOLETO, Gustavo Sousa; ALVES JUNIOR, Aderaldo Costa; FIGUEIREDO, Eberval Gadelha; OTOCH, Jose Pinhata; TEIXEIRA, Manoel JacobsenObjective: Intracranial hypertension (IN) develops in approximately 50% of all patients with severe traumatic brain injury (TBI). Therefore, it is very important to identify a suitable animal model to study and understand the pathophysiology of refractory IH to develop effective treatments. Methods: We describe a new experimental porcine model designed to simulate expansive brain hematoma causing IH. Under anesthesia, was simulated with a balloon insufflation. The IH variables were measured with intracranial pressure (ICP) parenchymal monitoring, epidural, cerebral oximetry, and transcranial Doppler (TCD). Results: None of the animals died during the experiment. The ICP epidural showed a slower rise compared with parenchymal ICP. We found a correlation between ICP and cerebral oximetry. Conclusion: The model described here seems useful to understand some of the pathophysiological characteristics of acute IH.
- Evaluation of cerebral hemodynamics by transcranial Doppler ultrasonography and its correlation with intracranial pressure in an animal model of intracranial hypertension(2022) SOARES, Matheus Schmidt; ANDRADE, Almir Ferreira de; BRASIL, Sergio; DE-LIMA-OLIVEIRA, Marcelo; BELON, Alessandro Rodrigo; BOR-SENG-SHU, Edson; NOGUEIRA, Ricardo de Carvalho; GODOY, Daniel Agustin; PAIVA, Wellingson SilvaBackground: Transcranial Doppler has been tested in the evaluation of cerebral hemodynamics as a non-invasive assessment of intracranial pressure (ICP), but there is controversy in the literature about its actual benefit and usefulness in this situation. Objective: To investigate cerebral blood flow assessed by Doppler technique and correlate with the variations of the ICP in the acute phase of intracranial hypertension in an animal model. Methods:An experimental animal model of intracranial hypertension was used. The experiment consisted of two groups of animals in which intracranial balloons were implanted and inflated with 4 mL (A) and 7 mL (B) for controlled simulation of different volumes of hematoma. The values of ICP and Doppler parameters (systolic [FVs], diastolic [FVd], and mean [FVm] cerebral blood flow velocities and pulsatility index [PI]) were collected during the entire procedure (before and during hematoma simulations and venous hypertonic saline infusion intervention). Comparisons between Doppler parameters and ICP monitoring were performed. Results: Twenty pigs were studied, 10 in group A and 10 in group B. A significant correlation between PI and ICP was obtained, especially shortly after abrupt elevation of ICP. There was no correlation between ICP and FVs, FVd or FVm separately. There was also no significant change in ICP after intravenous infusion of hypertonic saline solution. Conclusions:These results demonstrate the potential of PI as a parameter for the evaluation of patients with suspected ICP elevation.
conferenceObject CORRELATION BETWEEN INTRACRANIAL PRESSURE AND MEASUREMENT OF OPTIC NERVE SHEATH IN A SWINE MODEL OF INTRACRANIAL HYPERTENSION(2014) JEMG, Robson Luis Amorim Brasil Ping; ANDRADE, Almir Ferreira de; PAIVA, Wellingson Silva; BELON, Alessandro R.; OLIVEIRA, Marcelo Lima de; AZEVEDO, Maira; BOR-SENG-SHU, Edson; FIGUEIREDO, Eberval Gadelha; OTOCH, Jose Pinhata; TEIXEIRA, Manoel Jacobsen- Effects of ischemic preconditioning in a pig model of large-for-size liver transplantation(2015) LEAL, Antonio Jose Goncalves; TANNURI, Ana Cristina Aoun; BELON, Alessandro Rodrigo; GUIMARAES, Raimundo Renato Nunes; COELHO, Maria Cecilia Mendonca; GONCALVES, Josiane de Oliveira; SERAFINI, Suellen; MELO, Evandro Sobroza de; TANNURI, UenisOBJECTIVE: In most cases of pediatric liver transplantation, the clinical scenario of large-for-size transplants can lead to hepatic dysfunction and a decreased blood supply to the liver graft. The objective of the present experimental investigation was to evaluate the effects of ischemic preconditioning on this clinical entity. METHODS: Eighteen pigs were divided into three groups and underwent liver transplantation: a control group, in which the weights of the donors were similar to those of the recipients, a large-for-size group, and a large-for-size + ischemic preconditioning group. Blood samples were collected from the recipients to evaluate the pH and the sodium, potassium, aspartate aminotransferase and alanine aminotransferase levels. In addition, hepatic tissue was sampled from the recipients for histological evaluation, immunohistochemical analyses to detect hepatocyte apoptosis and proliferation and molecular analyses to evaluate the gene expression of Bax ( pro-apoptotic), Bcl-XL (anti-apoptotic), c-Fos and c-Jun (immediate-early genes), ischemia-reperfusion-related inflammatory cytokines (IL-1, TNF-alpha and IL-6, which is also a stimulator of hepatocyte regeneration), intracellular adhesion molecule, endothelial nitric oxide synthase (a mediator of the protective effect of ischemic preconditioning) and TGF-beta (a pro-fibrogenic cytokine). RESULTS: All animals developed acidosis. At 1 hour and 3 hours after reperfusion, the animals in the large-for-size and large-for-size + ischemic preconditioning groups had decreased serum levels of Na and increased serum levels of K and aspartate aminotransferase compared with the control group. The molecular analysis revealed higher expression of the Bax, TNF-alpha, I-CAM and TGF-beta genes in the large-for-size group compared with the control and large-for-size + ischemic preconditioning groups. Ischemic preconditioning was responsible for an increase in c-Fos, IL-1, IL-6 and e-NOS gene expression. CONCLUSION: Ischemia-reperfusion injury in this model of large-for-size liver transplantation could be partially attenuated by ischemic preconditioning.
- Pentoxifylline associated to hypertonic saline solution attenuates inflammatory process and apoptosis after intestinal ischemia/reperfusion in rats(2014) MARQUES, Geraldo Magela Nogueira; RASSLAN, Roberto; BELON, Alessandro Rodrigo; CARVALHO, Juliana Gonalves; NETO, Raphael Felice; RASSLAN, Samir; UTIYAMA, Edivaldo Massazo; MONTERO, Edna Frasson de SouzaPURPOSE: To evaluate intestinal inflammatory and apoptotic processes after intestinal ischemia/reperfusion injury, modulated by pentoxifylline and hypertonic saline. METHODS: It was allocated into four groups (n=6), 24 male Wistar rats (200 to 250g) and submitted to intestinal ischemia for 40 min and reperfusion for 80 min: IR (did not receive any treatment); HS group (Hypertonic Saline, 4ml/kg-IV); PTX group (Pentoxifylline, 30mg/kg-IV); HS+PTX group (Hypertonic Saline and Pentoxifylline). All animals were heparinized (100U/kg). At the end of reperfusion, ileal fragments were removed and stained on hematoxylin-eosin and histochemical studies for COX-2, Bcl-2 and cleaved caspase-3. RESULTS: The values of sO(2) were higher on treated groups at 40 minutes of reperfusion (p=0.0081) and 80 minutes of reperfusion (p=0.0072). Serum lactate values were lower on treated groups after 40 minutes of reperfusion (p=0.0003) and 80 minutes of reperfusion (p=0.0098). Morphologic tissue injuries showed higher grades on IR group versus other groups: HS (p=0.0006), PTX (p=0.0433) and HS+PTX (p=0.0040). The histochemical study showed lesser expression of COX-2 (p=0.0015) and Bcl-2 (p=0.0012) on HS+PTX group. A lower expression of cleaved caspase-3 was demonstrated in PTX (p=0.0090; PTXvsIR). CONCLUSION: The combined use of pentoxifylline and hypertonic saline offers best results on inflammatory and apoptotic inhibitory aspects after intestinal ischemia/reperfusion.
- Inflammatory markers assessment in an animal model of intracranial hypertension: a randomized trial(2021) SANTO, Marcelo Prudente do Espirito; FARIA, Caroline Silverio; SOLLA, Davi Jorge Fontoura; PIPEK, Leonardo Zumerkorn; BELON, Alessandro Rodrigo; JENG, Brasil Ping; ANDRADE, Almir Ferreira de; TEIXEIRA, Manoel Jacobsen; PAIVA, Wellingson SilvaBackground: Intracranial hypertension (ICH) is a common final pathway of most neurosurgical pathologies and leads to poor prognosis if not detected and treated properly. Inflammatory markers have been assessed in clinical scenarios of neurological injuries, in which systemic and brain tissue aggressions may introduce bias. There is a lack of studies under controlled settings to isolate the ICH effect on inflammation. This study aims to evaluate the effects of ICH on the serum concentration of cytokines as biomarkers of neuroinflammation in an experimental model which isolates ICH from potential confounding variables. Methods: An established model of ICH using an intracerebral pediatric bladder catheter and a multisensor intraparenchymal catheter was used in adult pigs (Sus domesticus). The animals were randomly allocated to 2 groups based on the catheter balloon volume used to simulate the ICP increase (4 ml or 7 ml). Cytokines were measured in 4 timepoints during the experiment: (1) 15 min before balloon insufflation; (2) 5 min after insufflation; (3) 125 min after insufflation; (4) 60 min after deflation. The following cytokines were measured IL-1 alpha; IL-1 beta; IL-1ra; IL-2; IL-4; IL-6; IL-8; IL-10; IL-12; IL-18; TNFa. Generalized estimating equations were modeled to compare the ICP and cytokines values between the groups along the experiment. The study sample size was powered to detect interactions between the groups and the study moments with an effect size (f) of at least 0.3. The ARRIVE checklist was followed. Results: A total of 20 animals were studied (10 in each group, 4 ml or 7 ml balloon volume insufflation). The animal model was successful in increasing the ICP along the moments of the experiment (p < 0,001) and in creating an ICP gradient between the groups (p = 0,004). The interaction term (moment x group) was also significant (p < 0,001). There was a significant association between ICP elevation and most cytokines variation. The cytokines IL-1 alpha, IL-1 beta, IL1-ra, IL-6, IL-12, and IL-18 increased, whereas IL-2, IL-4, and TNF-alpha decreased. IL-10 did not vary significantly in response to the ICP elevation. Conclusion: The serum concentration of cytokines varied in response to intracranial hypertension. The study demonstrated the specific changes in each cytokine afterintracranial hypertension and provides key information to guide neuroinflammation clinical research. The proposed experiment was successful as an animal model to the study of neuroinflammation biomarkers.
- The Effects of Induction and Treatment of Intracranial Hypertension on Cerebral Autoregulation: An Experimental Study(2018) OLIVEIRA, Marcelo de Lima; SALINET, Angela Macedo; NOGUEIRA, Ricardo de Carvalho; BELON, Alessandro Rodrigo; PAIVA, Wellingson Silva; JENG, Brasil Chian Ping; TEIXEIRA, Manoel Jacobsen; BOR-SENG-SHU, EdsonBackground. This study aimed to analyse cerebral autoregulation (CA) during induction and treatment of intracranial hypertension (ICH) in an experimental model. Materials and Methods. Landrace and Duroc piglets were divided into mild and severe ICH groups. Four or seven millilitres of saline solution was infused into paediatric bladder catheter inserted in the parietal lobe (balloon inflation). After 1.5 h, a 3% saline solution was infused via venous catheter, and 30 min later, the bladder catheter balloon was deflated (surgery). The cerebral static autoregulation (sCA) index was evaluated using cerebral blood flow velocities (CBFV) obtained with Doppler ultrasound. Results. Balloon inflation increased ICP in both groups. The severe ICH group showed significantly lower sCA index values (p=0.001, ANOVA) after balloon inflation (ICH induction) and a higher sCA index after saline injection (p=0.02) and after surgery (p=0.04). ICP and the sCA index were inversely correlated (r=-0.68 and p<0.05). CPP and the sCA index were directly correlated (r=0.74 and p<0.05). Conclusion. ICH was associated with local balloon expansion, which triggered CA impairment, particularly in the severe ICH group. Moreover, ICP-reducing treatments were associated with improved CA in subjects with severe ICH.
conferenceObject CORRELATION BETWEEN INTRACRANIAL PRESSURE AND MEASUREMENT OF OPTIC NERVE SHEATH IN A SWINE MODEL OF INTRACRANIAL HYPERTENSION(2014) JEMG, Robson Luis Amorim Brasil Ping; ANDRADE, Almir Ferreira de; PAIVA, Wellingson Silva; BELON, Alessandro R.; OLIVEIRA, Marcelo Lima de; AZEVEDO, Maira; BOR-SENG-SHU, Edson; FIGUEIREDO, Eberval Gadelha; OTOCH, Jose Pinhata; TEIXEIRA, Manoel Jacobsen